Glaucoma is the most common cause of blindness and the second leading cause of irreversible blindness among black Americans in the United States (Congdon et al. (2004) ARCH. OPHTHALMOL. 122: 477-85). Glaucoma is also the leading cause of blindness among U.S. Hispanics (Congdon et al. (2004) supra, Rodriguez et al. (2002) OPHTHALMOL. 109:737-43). Glaucoma is a progressive optic neuropathy, which can induce blindness without any warning and often without symptoms.
Glaucoma is characterized by a buildup of fluid within the eye, often causing an increase in intraocular pressure (IOP). The pressure increase damages the optic nerve, resulting in cellular death and vision loss. In a healthy eye, the fluid that contains nutrients and that bathes the eye is continuously drained and replenished. However, in a person with glaucoma, this fluid either does not drain properly or is created in excess, resulting in an increase in intraocular pressure. The elevated intraocular pressure, if left untreated, eventually damages the optic nerve.
As a result, lowering intraocular pressure using medical or surgical therapy is the main therapeutic approach to control and treat this common condition. The currently available treatments, however, have their own problems. Most medications have side effects, lose their efficacy, and require patients' life time compliance. Surgical methods have a high complication risk. Ciliary body destruction by cryotherapy or laser irradiation represents a useful alternative for the management of glaucoma resistant to other modes of therapy (Bietti (1950) JAMA, 142:889-897, Wekers et al. (1961) AM. J. OPHTHALMOL. 52:156-63, Smith et al. (1969) AM. J. OPHTHALMOL. 67:100-10). However, the current cyclodestructive techniques have a high rate of side-effects including loss of vision, hypotony, macular edema or phthisis bulbi (Beckman et al. (1984) AM. J. OPHTHALMOL. 98:788-95, Haddad (1981) WIEN. KLIN. WOCHENSCHR. SUPPL. 126:1-18, Kaiden et al. (1979) ANN. OPHTHALMOL. 11:1111-3).
Accordingly, there is still an ongoing need for new methods for treating glaucoma, which can reduce intraocular pressure for extended periods of time, but without the side effects of other currently available treatments.